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Replacing parking light bulbs...

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AMX2020 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMX2020 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/13/2020 at 10:21am
Yes, it could be a problem with the switch. That said, I did come across a short Youtube video last night where the poster demonstrates how some LED bulbs do not work with older cars. See link below.

https://www.youtube.com/watch?v=tci97uxfptA
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMX2020 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/13/2020 at 10:36am
Thanks for the info.

I will try giving the wires a gentle tug while inserting the bulb.

I was also thinking of filing the contacts down slightly on the incandescent bulb so they are roughly the same height as the contacts on the LED bulbs. 

I picked up a multimeter yesterday and will check to see if any power is getting to the socket(s) when the switch is in the first position.

Didn't think I would run into such problems changing bulbs...


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Post Options Post Options   Thanks (0) Thanks(0)   Quote ramblinrev Quote  Post ReplyReply Direct Link To This Post Posted: Feb/13/2020 at 11:53am
I think we're steering you in the right direction, but let us know. The first switch detent should surely turn on the parking lights, tail lights, side markers. The full 'pull' on the switch should add the headlights (and in '68, shut off the parking lights. In '69 and up, the parking lights stay on with the headlights on.)

Good luck!


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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigbad69 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/13/2020 at 12:01pm
Originally posted by AMX2020 AMX2020 wrote:

Yes, it could be a problem with the switch. That said, I did come across a short Youtube video last night where the poster demonstrates how some LED bulbs do not work with older cars. See link below.

Interesting. The OE flashers are open/closed only. They do not ever ground the bulb terminals. The need for that in LED bulbs is unknown to me. It must depend upon the design approach taken in the LED bulbs to mimic bright and dim filaments.

A quick check to determine if this is your problem would be to disconnect the flasher unit, then try the park lights. If they are now working normally, that video explains your problem.

OK. you have already removed the LED bulbs. Try putting them back in and doing the test before switching to incandescent bulbs. If the whole car has been switched to LED, you might introduce new problems by running a hybrid LED/incandescent system.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Feb/13/2020 at 9:35pm
That youtube guy is just wrong. The flasher doesn't ground the lamp, that's nothing to do with anything.

"old fashioned" flashers, non-electronic types, like AMC used, are very much like the old Rambler dash regulators. They are electro-mechanical devices, a heater and a bimetallic switch, essentially a thermostat, wired like this:


BATTERY -------> turn switch -------> flasher -------> lamp -------> GROUND

When the switch is off, the lamp is off, and the flasher mechanism is cold inside. When switch turns ON, current flows. A coil of wire, a tiny heater, wrapped around the bimetallic switch, heats up. For about 1/3rd of a second current flows, lamp lights, the heater in the flasher warms up, causing  the bi-metal to move, opens the circuit, the lamp goes off. It's metal, has mass, about 300 mS later, it cools enough to bend back, contact! light, repeat. That's the sound you hear, a physical switch going click click.

An 1157 lamp draws about 2 amps -- that's a lot of current! So there's plenty of power for the above to happen.

LEDs draw maybe 0.1 or 0.3 amps. NOT ENOUGH CURRENT. FLasher doesn't flash! Or it "microflashes", rapidly etc.

ELECTRONIC flashers, later model cars moved to three-wire flashers, 12V in, flasher out, and ground. These use an electronic circuit, with explicit timing elements, to get the 2 to 3 times per second flashing, instead of side effects of current draw. The circuit requires ground for reasons of electronic design.

That's why if you parallel LED lamps with a resistor (that gets hot, etc) the old flashers work. The resistor wastes the power the old lamp did, while the LED makes the light.

You can buy two-wire flashers that work with LEDs. Thats what I did, to run red LED 2357 tail lamps on my 68 AMerican, which I did because the lenses are getting clear, somehow, and the sockets old and corroded, and bad connections due to the high currents and heat of lamps. The red LEDs make more light for less current, but needs the modern flasher to flash.




Edited by tomj - Feb/13/2020 at 9:37pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Feb/13/2020 at 9:38pm
In front, at least, it's surprising that the marker lamps, sockets, etc last at all. Out in front of sand, rain, rocks, blasted at the lens and housing the whole time you're driving! 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Feb/13/2020 at 10:07pm
I had a '69 and the front marker / parking / turn signal lights in the bumper
were on when only parking lights were on, AND were on when headlights were on.
I did not know it was different on 1968 Models...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMX2020 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/14/2020 at 3:55pm
Well I gave up on getting the Sylvania 1157 bulbs into the front parking lights, they just won't go in there. I have no problem putting them in the rear taillights. I put the LED lights back in at the front. I barely got those in.

So, I am back to where I started, turns signals are OK, 4 way flashers are OK, and the side markers and parking lights come on when I activate the headlights. I think this is fine, I don't plan on using the parking lights anyway but I need the car to pass a provincial inspection before I can register the car and buy insurance. I'm a little concerned that the car might fail the inspection. Running lights are not required on a car older than 15 years here in Canada so the car should not really fail over front parking lights not working, but you never know, I hear the inspectors can be quite fussy. They might insist that all lights function as they would have from the factory. I doubt they would think the front parking lights should be on or off when the headlights are activated but they will likely notice that the rear taillights come on when the headlight switch is at the first (parking) position but there is nothing happening at the front. 

Thanks for all the feedback on this issue.

~ Mark


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Post Options Post Options   Thanks (0) Thanks(0)   Quote ramblinrev Quote  Post ReplyReply Direct Link To This Post Posted: Feb/14/2020 at 4:50pm
Good luck. I think it should pass! Hard to understand what might have happened to those front sockets, if you can't get the correct bulbs in. But unless you run into a fussy inspector, don't lose any sleep over it!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote george w Quote  Post ReplyReply Direct Link To This Post Posted: Feb/15/2020 at 10:26am
I suspect the problem with the seating of your 1157 bulbs in the parking sockets has to do with dirt or corrosion build up within the socket below the phenolic contact plate. This is preventing the contact plate from moving downward as the bulb is inserted. This build up is likely preventing the springs on the contact wires below the plate from compressing as the bulb is pressed in. I would try removing the housing from the bumper and soaking the inside of the socket with a penetrating oil like PB Blaster or WD-40. You should be able to easily push the contact plate down into the socket and feel it being pushed back by the springs below. You can help this process along by pulling back on the wires exiting the rear of the lamp socket while simultaneously pushing in on the contact plate.

As for the parking lights staying on with the headlights, AMC changed the parking light wiring to keep the parking lights on with the headlights which became the norm for just about all American cars from 1969 and up. This may have been a federal requirement for safety reasons. This was a simple change as all they had to do was combine the parking light circuit with the tail light circuit. A simple modification to the headlight switch can be done to keep the parking lights on with the tail lights on 68 and earlier cars. All that needs to be done is to solder a short 1" wire jumper to the bases of the "P" lug and the "R" lug of the headlight switch. This ties the parking and tail light terminals together. A simple paper clip or a short piece of bare copper wire ( like the bare copper ground conductor in simple household Romex wire )works fine for this purpose. The jumper is thin enough so that it will not interfere with the seating of the harness plug into the switch.
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